1. Field of Invention
This invention relates to a solar energy collector. More particularly, it relates to a device that collects a surprisingly large amount of solar energy without having to track the sun.
2. Brief Statement of the Prior Art
The depletion of fossil fuels, together with their increasing cost, has led to the exploration of alternative energy sources. The field of nuclear energy has seen much recent development, but its inherent danger and cost tend to detract from its worth. The use of solar energy has the advantage of relative safety, low capital cost and (of course) free fuel. However, using the radiated energy of the sun has some recognized disadvantages. The chief disadvantage is the relatively low energy flux. That is, while the energy emitted from the sun is collectively enormous, a relatively small amount falls on the earth per square meter. Moreover, this small amount is variable, depending on weather conditions, time of day, time of year, and latitude. It has been recognized as desirable to maximize the energy flux by, to the extent possible, negating the adverse effect of these variable conditions. Naturally, the effects of weather and night cannot be overcome except by energy storage. However, the effects of time of year, time of day, and latitude can be minimized by selective alignment of the energy absorbing device.
In general, it is desirable that the energy absorbing device (which can be assumed to be planar when compared to the distance to the sun) be normal to the sun. Further, it is desirable that lenses be used, so a relatively larger amount of energy be concentrated on a relatively smaller area.
The problem with aligning the absorbing device with the sun, of course, is the apparent movement of the sun caused by the rotation of the earth, both about its own axis and about the sun. Machinery can be built which will move the absorber to account for this apparent movement of the sun. Regretably, such machinery is expensive when compared with the low available energy flux. Further, it must eventually break down and require maintenance, while a solar energy collector is more preferably left unattended for extensive periods of time. Thus, it is preferred that at least the seasonal variation be adjusted for by a permanent positioning relative to that movement. This permanent positioning will result in acceptable decreases in efficiency from the optimum as the seasons change.
With respect to concentrating the sun's rays, a conventional optical lens is far too expensive--again because of the low energy flux. Thus, mirrors or mirrored surfaces and prismatic lenses. Prismatic lenses are commonly known as Fresnel lenses. The problem of daily variations and lenses have been addressed by U.S. Pat. No. 3915,148; U.S. Pat. No. 4,957,048; West U.S. Pat. No. 2,872,915; and combinations thereof U.S. Pat. No. 895,761.